Well what you have left is Saint Augustine that was neglected most likely by the house sitting up for sale for long time without being waters, and what dry conditions did not kill cinch bugs ate.

There is only one real way to fix this if you want Saint Augustine or Bermuda, use some of that money you saved on the deal; regrade the area and lay new sod down.

Im in fort myers and just went with an empire turf lawn and love it.

Here are questions to ask.
Are you going to be running irrigation, if not, do not grow bermuda or St aug. Bahia will grow very well with no irrigation, you need to seed Bahia by June. Soon as the rainy season starts.

Are you going to have a dog or lots of traffic on the lawn? If you have this, St aug is out, cant handle traffic. Bermuda, Empire or Bahia will do good, bermuda being the best for traffic.

Are you going to fertilize and use herbicide. If not, go with Empire or Bahia, they need little fertilizer to none.

Like I said, I went with Empire turf (zoysia). Its bread to thrive it wet hot summers. I have irrigation for the dry months. You only need to fertilize 3 times a year.

The thing I do not like about St Aug (also called flortam down here) its very course and rough. You can only use one weed killer and if that does not work then your stuck with weeds to pull by hand.
Empire can handle almost all weed killers, even low concentration of roundup.

Long post, I know.

I would spray the entire yard with round up (get a generic online, 30 bucks for a gallon of concentrated, 41%, Ill post a link). Get a dial sprayer for 10 bucks at a store, and apply. This will kill all grass and weeds so your left with sand. Now, wait two weeks and either seed or sod the yard with your choice of grass.

Done. Thats my 2c.

This is what I got, I used about 3/4 of a gallon to spray a half acre.
You might want to buy a smaller container.

http://www.amazon.com/BONIDE-PRODUCTS-KLEENUP-41-CONCENTRATE/dp/B003AYUX3W/ref=sr_1_sc_3?ie=UTF8&s=home-garden&qid=1269994294&sr=1-3-spell

Here is a link that might be useful: Kleenup

I had figured on having to start from scratch and resod completely, but I was just trying to see if there was any other way. We are fencing the back yard in a few weeks and will most likely resod the front first, and try and save the back since it is not burnt and completely dead like the front. I guess the question now is..do i do it myself or have a company do it for me...?

Its on how bad you want it. If you are going with St Aug or floratam then go to lowes or Homedepot and get a tray of plugs. They will fill in and cover the yard by the end of the year.
If you want the lawn, hire someone to sod the yard, or do it yourself. Its easy, how good is your back?

-Bill

My inclination would be to resurrect what you have. St Augustine is resiliant and can fill in pretty well in one season.

Set your mower to the highest setting and don't mow until you have grass (not weeds) that high. If your weeds get tall faster, take them down to the roots with a string type weed whacker.

Start watering weekly and water deeply. Use tuna cans to measure how long it takes to put an inch of water down and water for that long when you water. Then watch the grass to see if it tells you it's thirsty. It will lose its luster and change to a slightly gray-green. Then water it immediately. Next time don't wait quite that long. St Aug is not drought tolerant. Watering daily is a bad idea for many reasons. It is too late in the morning to get into them.

Since you don't have actively growing grass yet, you might use an organic fertilizer on it now. Synthetic will not do anything unless the grass has started to grow. The organic takes a little time to get going so the timing is probably good for that.

The weeds in your last picture are easy to pull when the soil is slightly moist. Do it as soon as you see them or you will regret it.